Metal component sturcture and metal component swaging method

ABSTRACT

A metal component structure includes a metal ball and a metal component. The metal ball has an outer diameter. The metal component includes a hole into which the metal ball is press-fitted. The hole includes a central axis, an opening edge, a stopper, and a tapered part. The metal ball is inserted into the hole through the opening edge. The stopper is provided between the opening edge and a center of the metal ball in a direction of the central axis and has an inner diameter smaller than the outer diameter of the metal ball. The tapered part is provided from the opening edge toward the stopper and has an inner diameter decreasing from the opening edge toward the stopper.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U. S. C. §119 to Japanese Patent Application No. 2015-246354, filed Dec. 17, 2015. The contents of this application are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a metal component structure and a metal component swaging method.

Discussion of the Background

Japanese Patent No. 5620887 and Japanese Examined Utility Model Registration Application Publication No. Hei 7-039539 mentioned below have publicly disclosed a method of performing, in one step by use of a single tool, both steps of press-fitting a metal ball into a hole opened in the surface of a metal part (a metal component), and preventing disengagement of the metal ball by swaging an opening of the hole.

A swaging tool described in Japanese Patent No. 5620887 includes a pressing portion 52 having a flat annular tip end surface 52a, and is configured to press-fit a metal ball 15 into a hole 11 in a metal part (a metal component), by moving the swaging tool axially with the inner circumferential edge of the tip end surface 52a abutting on the metal ball 15 set in an opening of the hole 11, and also prevent disengagement of the metal ball 15, by swaging the periphery of the opening of the hole 11 radially inward with the flat annular tip end surface 52a.

Meanwhile, a swaging tool described in Japanese Examined Utility Model Registration Application Publication No. Hei 7-039539 includes a swaging tool part 4 fixed to the tip end of a tool main body 10, and a pressing tool 3 axially penetrating the center of the swaging tool part 4 and energized by a spring 5 in such a direction as to protrude from the swaging tool part 4, and is configured to press-fit a metal ball 2 into a hole 1 by axially moving the swaging tool with the pressing tool 3 fixed to the tool main body 10, and then prevent disengagement of the metal ball 2 by swaging two points around an opening of the hole 1 with the swaging tool part 4, by axially moving the swaging tool further with the pressing tool 3 released from the tool main body 10.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a metal component swaged structure in which, to prevent disengagement of a metal ball press-fitted into a hole opened in a surface of a metal component, a swaged part having a smaller diameter than an outer diameter of the metal ball is formed along the entire circumference of an opening of the hole, characterized in that an inner diameter gradually decreases from an opening edge portion of the hole toward the inside of the hole, down to the swaged part.

According to another aspect of the present invention, a metal component structure includes a metal ball and a metal component. The metal ball has an outer diameter. The metal component includes a hole into which the metal ball is press-fitted. The hole includes a central axis, an opening edge, a stopper, and a tapered part. The metal ball is inserted into the hole through the opening edge. The stopper is provided between the opening edge and a center of the metal ball in a direction of the central axis and has an inner diameter smaller than the outer diameter of the metal ball. The tapered part is provided from the opening edge toward the stopper and has an inner diameter decreasing from the opening edge toward the stopper.

According to further aspect of the present invention, a metal component swaging method includes providing a metal ball at an opening edge of a hole provided in a metal component. The hole has a central axis. The metal ball is pressed in a direction of the central axis using a swaging tool such that a metal ball press-fitting portion of the swaging tool abuts on the metal ball to press-fit the metal ball into the hole. The press-fitting portion is positioned around the central axis. A swaging portion of the swaging tool is pressed onto the metal component in the hole to provide a stopper between the opening edge and a center of the metal ball in the direction of the central axis. The swaging portion is provided around the metal ball press-fitting portion. An outer diameter of the swaging portion decreases toward the metal ball press-fitting portion.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

FIG. 1 is a longitudinal section of a metal part and a swaging tool. (First embodiment)

FIG. 2 is a perspective view of the swaging tool. (First embodiment)

FIG. 3 is a diagram showing steps of press-fitting a metal ball and swaging. (First embodiment)

FIG. 4 is a diagram showing a state where the steps of press-fitting the metal ball and swaging are completed. (First embodiment)

FIG. 5 is a graph showing the relation between a protrusion amount of the metal ball from a flat surface, and a swaged amount of a swaging part. (First embodiment)

FIG. 6 is a diagram corresponding to FIG. 2. (Second embodiment)

FIG. 7 is a diagram corresponding to FIG. 3. (Second embodiment)

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings.

First Embodiment

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5.

As shown in FIGS. 1 to 4, a hole 11 a having a constant inner diameter and forming a hydraulic pathway for supplying lubricating oil to a lubricated part, is drilled in a metal part 11 (a metal component 11) such as a crankshaft of an engine. A flat surface 11 d is spot-faced around an opening 11 c of the hole 11 a, on a surface 11 b of the metal part 11. The spot-faced flat surface 11 d is perpendicular to an axis L (a central axis L) of the hole 11 a. The spot facing for forming the flat surface 11 d need not be performed, if the surface 11 b of the metal part 11 around the opening 11 c of the hole 11 a is a plane perpendicular to the axis L.

A metal ball 12 is press-fitted into the hole 11 a from the opening 11 c to prevent leakage of the lubricating oil from the hole 11 a, and a swaged part 11 e (a stopper 11 e) protruding radially inward is formed for 360 degrees on the inner circumference of the opening 11 c of the hole 11 a, to prevent disengagement of the press-fitted metal ball 12 from the hole 11 a. The outer diameter of the metal ball 12 is slightly larger than an inner diameter D1 of the hole 11 a. An inner diameter D2 of the swaged part 11 e is 50 μm to 150 μm smaller than the outer diameter D1 of the metal ball 12, for example. Hence, even if the press-fitted part becomes loose, abutment of the outer surface of the metal ball 12 on the swaged part 11 e prevents disengagement of the metal ball 12.

As shown in FIGS. 1 and 2, a swaging tool 13 for simultaneously press-fitting the metal ball 12 into the hole 11 a and swaging the inner circumference of the opening 11 c of hole 11 a is formed into a rotor having the axis L, and includes: a tool main body portion 13 a formed into a column having a constant diameter; a swaging portion 13 c formed on the tip end side of the tool main body portion 13 a; and a metal ball press-fitting portion 13 d formed on the radially inner side of the swaging portion 13 c.

The swaging portion 13 c is a tapered surface (conical surface) whose diameter decreases toward the tip end side of the tool main body portion 13 a, and has a minimum outer diameter D4 set smaller than the inner diameter D1 of the hole 11 a. The metal ball press-fitting portion 13 d is a tapered surface (conical surface) whose diameter decreases toward the base end side of the swaging tool 13 from the inner circumference of the swaging portion 13 c, and its axis coincides with the axis L of the swaging tool 13.

Next, a description will be given of effects of the embodiment of the present invention having the above configuration.

First, as shown in FIG. 1, the metal ball 12 is set in the opening 11 c of the hole 11 a in the metal part 11. At this time, although both of the inner diameter of the hole 11 a and the outer diameter of the metal ball 12 are D1, the outer diameter of the metal ball 12 is set slightly larger than the inner diameter of the hole 11 a. Hence, the metal ball 12 is locked onto the opening 11 c.

Next, the metal ball press-fitting portion 13 d of the swaging tool 13 is brought into contact with the metal ball 12 with the axis L of the swaging tool 13 aligned with the axis L of the hole 11 a, and when the swaging tool 13 is pressed into the hole 11 a as in FIG. 3, the metal ball 12 pressed by the metal ball press-fitting portion 13 d is press-fitted into the hole 11 a from the opening 11 c. At this time, the metal ball press-fitting portion 13 d formed of the conical surface and the metal ball 12 are in line-to-line contact along a circular contact line. Hence, a pressing load can be applied precisely along the axis L direction on the metal ball 12 to press-fit it into the hole 11 a in a stable position, while preventing application of local load on the metal ball 12. Additionally, since the conical surface of the swaging portion 13 c comes into contact with the opening 11 c of the hole 11 a, and the conical surface of the metal ball press-fitting portion 13 d comes into contact with the spherical surface of the metal ball 12, the axis L of the swaging tool 13 is automatically aligned with the axis L of the hole 11 a. Thus, the metal ball 12 can be press-fitted more stably.

When the swaging tool 13 is pressed into the hole 11 a, the conical swaging portion 13 c of the swaging tool 13 abuts on the opening 11 c of the hole 11 a in the metal part 11, and plastically deforms and presses the wall around the opening 11 c into the inner circumference side of the hole 11 a. This forms the swaged part 11 e having the inner diameter D2 (<D1) and bulging radially inward (at a tapered part), in the opening 11 c of the hole 11 a as shown in FIG. 4.

Although a swaged amount α (see FIG. 4) of the swaged part 11 e needs to be set not smaller than 50 μm, for example, to surely prevent disengagement of the metal ball 12, it is difficult to visually confirm or directly confirm with an instrument whether or not the swaged amount α is not smaller than 50 μm. However, according to the embodiment, it is possible to confirm whether or not the swaged amount α is not smaller than 50 μm, by measuring an upward protrusion amount d of the top of the metal ball 12 from the flat surface 11 d.

A graph in FIG. 5 shows the relation between the protrusion amount d of the top of the metal ball 12 from the flat surface 11 d, and the swaged amount α of the swaged part 11 e. The graph shows that the larger the protrusion amount d of the metal ball 12, that is, the smaller the press-fit depth of the metal ball 12, the smaller the swaged amount α of the swaged part 11 e. Hence, a protrusion amount d of about 0.7 mm or less of the metal ball 12 is sufficient to ensure a 50 μm swaged amount α to withstand a 300 kgf pullout load, for example. The protrusion amount d of the metal ball 12 can be confirmed easily by use of general measuring equipment such as a dial gauge.

As has been described, according to the embodiment, the swaging portion 13 c of the swaging tool 13 has a conical shape. Hence, after press-fitting of the metal ball 12, the inner diameter of the hole 11 a in the metal part 11 gradually decreases from an opening edge portion 11 f toward the inside of the hole 11 a, down to the swaged part 11 e (see FIG. 4). By thus adopting the conical swaging portion 13 c, the wide area around the opening need not be swaged with a large swaging load, and a local load need not be applied on the opening. This prevents cracks in the metal part 11 or deterioration in durability of the swaging tool 13, and therefore solves problems of the aforementioned Patent Documents 1 and 2.

Also, since the swaging portion 13 c and the metal ball press-fitting portion 13 d are integrated with the swaging tool 13, press-fitting of the metal ball 12 into the hole 11 a in the metal part 11 and forming of the swaged part 11 e can be completed in one step, even though the structure is simple and does not have a movable part. This can cut processing cost. Moreover, since the protrusion amount d of the metal ball 12 (press-fit depth of metal ball 12) and the swaged amount α of the swaged part 11 e have a constant relation, the swaged amount α can be managed easily based on the easily measurable protrusion amount d of the metal ball 12.

Also, the swaging tool 13 has the metal ball press-fitting portion 13 d that abuts on the flat surface 11 d of the metal part 11 to control the press-fit depth of the metal ball 12 into the hole 11 a. Hence, the wall of the metal part 11 can be prevented from bulging from the flat surface 11 d when swaging, and can be distributed to the swaged part 11 e side, so that the necessary swaged amount α can be ensured with less load, and the flat surface 11 d of the metal part 11 can be kept flat. This can increase accuracy in measuring the press-fit depth of the metal ball 12 relative to the flat surface 11 d.

In particular, when the surface of a crankshaft as the metal part 11 is soft-nitrided to increase hardness, the swaged part 11 e is likely to crack if press-fitting of the metal ball 12 and swaging are carried out after the soft nitriding. In this case, cracks can be more surely prevented by soft-nitriding the crankshaft together with the metal ball 12, after press-fitting the metal ball 12 and swaging.

Second Embodiment

Next, a second embodiment of the present invention will be described with reference to FIGS. 6 and 7.

A swaging tool 13 of the second embodiment includes a tool main body portion 13 a formed into a column having a constant diameter; a press-fit depth control portion 13 b formed on the tip end side of the tool main body portion 13 a; a swaging portion 13 c protruding to the tip end side from the press-fit depth control portion 13 b; and a metal ball press-fitting portion 13 d formed on the radially inner side of the swaging portion 13 c.

The press-fit depth control portion 13 b is an annular flat surface extending radially inward from the outer surface of the tool main body portion 13 a, and is perpendicular to an axis L of the swaging tool 13. The swaging portion 13 c is a tapered surface (conical surface) whose diameter decreases toward the tip end side of the swaging tool 13 from the inner circumference of the press-fit depth control portion 13 b, and has a maximum outer diameter D3 set larger than an inner diameter D1 of a hole 11 a, and a minimum outer diameter D4 set smaller than the inner diameter D1 of the hole 11 a. The metal ball press-fitting portion 13 d is a tapered surface (conical surface) whose diameter decreases toward the base end side of the swaging tool 13 from the inner circumference of the swaging portion 13 c, and its axis coincides with the axis L of the swaging tool 13.

When insertion of the swaging tool 13 is insufficient and swaging is accidentally completed before the press-fit depth control portion 13 b of the swaging tool 13 abuts on a flat surface 11 d of a metal part 11, the volume of wall pushed out by the swaging portion 13 c is insufficient to form a necessary swaged amount α.

However, according to this embodiment, since the distance between the press-fit depth control portion 13 b of the swaging tool 13 and the metal ball press-fitting portion 13 d is constant, an upward protrusion amount d (i.e., press-fit depth of metal ball 12) of the top of the metal ball 12 from the flat surface 11 d when the press-fit depth control portion 13 b of the swaging tool 13 abuts on the flat surface 11 d of the metal part 11 is constant (see FIG. 4). Hence, the press-fit depth of the metal ball 12 can be automatically adjusted to a constant value without particularly controlling the amount of movement of the swaging tool 13, and therefore a stable swaged amount α of the swaged part 11 e can be maintained.

Accordingly, by confirming abutment of the press-fit depth control portion 13 b of the swaging tool 13 on the flat surface 11 d of the metal part 11 upon completion of swaging, it can be assured that the swaging portion 13 c has pushed out a sufficient volume of wall and a necessary swaged amount α has been achieved. Whether or not the press-fit depth control portion 13 b of the swaging tool 13 has abutted on the flat surface 11 d of the metal part 11 upon completion of swaging can be easily confirmed, by measuring the upward protrusion amount d of the top of the metal ball 12 from the flat surface 11 d.

Additionally, although a part of the wall around an opening 11 c pushed out by the swaging portion 13 c is thrust upward toward the side of the flat surface 11 d of the metal part 11, the thrust wall is pressed down by the press-fit depth control portion 13 b. Thus, the flat surface 11 d can be kept flat, and the necessary swaged amount α of the swaged part 11 e can be ensured.

Although the embodiments of the present invention have been described above, various design changes can be made without departing from the gist of the invention.

For example, the metal part 11 according to the embodiments of the present invention is not limited to the crankshaft shown in the embodiments.

Also, the swaged structure according to the embodiments of the present invention is not limited to that shown in FIG. 4. That is, the opening edge portion 11 f and a part of the flat surface 11 d leading to the opening edge portion 11 f may deform slightly and bulge upward as compared to the state before swaging, depending on the material of the metal part 11 or swaging conditions. However, the deformation need not be considered, as long as the inner diameter gradually decreases from the opening edge portion 11 f toward the inside of the hole 11 a, down to the swaged part 11 e.

Also, although the swaging portion 13 c of the embodiments is configured of a conical surface whose generatrix is a straight line, the generatrix of the swaging portion 13 c need not be a straight line, as long as the swaging portion is a surface of revolution whose outer diameter gradually decreases toward the tip end side of the swaging tool 13.

Also, although the metal ball press-fitting portion 13 d of the embodiments is configured of a conical surface whose generatrix is a straight line, the generatrix of the metal ball press-fitting portion 13 d need not be a straight line, as long as the metal ball press-fitting portion is a surface of revolution whose outer diameter gradually decreases toward the base end side of the swaging tool 13.

According to a first aspect of the present invention, proposed is a metal part swaged structure in which, to prevent disengagement of a metal ball press-fitted into a hole opened in a surface of a metal part, a swaged part having a smaller diameter than an outer diameter of the metal ball is formed along the entire circumference of an opening of the hole, characterized in that an inner diameter gradually decreases from an opening edge portion of the hole toward the inside of the hole, down to the swaged part.

Also, according to a second aspect of the present invention, proposed is a metal part swaging method for forming the swaged part according to the first aspect of the present invention by use of a swaging tool, characterized in that: the swaging tool includes a metal ball press-fitting portion that abuts on the metal ball to press-fit the metal ball into the hole, and a swaging portion that has an outer diameter gradually decreasing toward the metal ball press-fitting portion and forms the swaged part; and press-fitting of the metal ball into the hole and forming of the swaged part are carried out simultaneously, by use of the swaging tool.

Also, according to a third aspect of the present invention, proposed is a metal part swaging method characterized in that, in addition to the configuration according to the second aspect of the present invention, the metal ball press-fitting portion is formed of a conical surface.

Also, according to a fourth aspect of the present invention, proposed is a metal part swaging method characterized in that, in addition to the configuration according to the second or the third aspect of the present invention, the swaging portion is formed of a conical surface.

Also, according to a fifth aspect of the present invention, proposed is a metal part swaging method characterized in that, in addition to the configuration according to any one aspect of the second to fourth aspects of the present invention, the swaging tool includes a press-fit depth control portion that abuts on a surface of the metal part to control a press-fit depth of the metal ball into the hole.

According to the first aspect of the present invention, to prevent disengagement of the metal ball press-fitted into the hole opened in the surface of the metal part, the swaged part having a smaller diameter than the outer diameter of the metal ball is formed along the entire circumference of the opening of the hole. Since the inner diameter gradually decreases from the opening edge portion of the hole toward the inside of the hole, down to the swaged part, the wide area around the opening need not be swaged with a large swaging load, and also a local load need not be applied on the opening. This prevents cracks in the metal part or deterioration in durability of the swaging tool.

Also, according to the second aspect of the present invention, the swaging tool includes a metal ball press-fitting portion that abuts on the metal ball to press-fit the metal ball into the hole, and a swaging portion that has an outer diameter gradually decreasing toward the metal ball press-fitting portion and forms the swaged part, and press-fitting of the metal ball into the hole and forming of the swaged part are carried out simultaneously, by use of the swaging tool. Hence, press fitting of the metal ball and swaging can be completed in one step, so that processing cost can be cut. Moreover, since the press-fit depth of the metal ball and the swaged amount have a constant relation, the swaged amount can be managed easily based on the press-fit depth of the metal ball. What is more, since the outer diameter of the swaging portion gradually decreases toward the metal ball press-fitting portion, the axis of the swaging tool can be automatically aligned when processing.

Also, according to the third aspect of the present invention, the metal ball press-fitting portion is formed of a conical surface. Hence, the metal ball press-fitting portion and the metal ball can be brought into line-to-line contact, to press-fit the metal ball in a stable position while preventing application of local load on the metal ball.

Also, according to the fourth aspect of the present invention, the swaging portion is formed of a conical surface. Hence, it is possible to prevent a sudden change in the relation between the amount of movement of the swaging tool and the swaging amount when swaging, and facilitate management of the swaged amount.

Also, according to the fifth aspect of the present invention, the swaging tool includes the press-fit depth control portion that abuts on the surface of the metal part to control the press-fit depth of the metal ball into the hole. Hence, the wall of the metal part can be prevented from bulging to the surface side when swaging, and can be pushed in to the swaged part side, so that a necessary swaged amount can be ensured with less load, and the surface of the metal part can be kept flat. Also, since the amount of movement of the swaging tool is kept constant by the press-fit depth control portion, a stable swaged amount of the swaged part can be maintained.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. 

What is claimed is:
 1. A metal component swaged structure in which, to prevent disengagement of a metal ball press-fitted into a hole opened in a surface of a metal component, a swaged part having a smaller diameter than an outer diameter of the metal ball is formed along the entire circumference of an opening of the hole, wherein an inner diameter gradually decreases from an opening edge portion of the hole toward the inside of the hole, down to the swaged part.
 2. A metal component swaging method for forming the swaged part according to claim 1 by use of a swaging tool, wherein: the swaging tool includes a metal ball press-fitting portion that abuts on the metal ball to press-fit the metal ball into the hole, and a swaging portion that has an outer diameter gradually decreasing toward the metal ball press-fitting portion and forms the swaged part; and press-fitting of the metal ball into the hole and forming of the swaged part are carried out simultaneously, by use of the swaging tool.
 3. The metal component swaging method according to claim 2, wherein the metal ball press-fitting portion is formed of a conical surface.
 4. The metal component swaging method according to claim 2, wherein the swaging portion is formed of a conical surface.
 5. The metal component swaging method according to claim 2, wherein the swaging tool includes a press-fit depth control portion that abuts on a surface of the metal component to control a press-fit depth of the metal ball into the hole.
 6. A metal component structure comprising: a metal ball having an outer diameter; and a metal component including a hole into which the metal ball is press-fitted, the hole comprising: a central axis; an opening edge through which the metal ball is inserted into the hole; a stopper provided between the opening edge and a center of the metal ball in a direction of the central axis and having an inner diameter smaller than the outer diameter of the metal ball; and a tapered part provided from the opening edge toward the stopper and having an inner diameter decreasing from the opening edge toward the stopper.
 7. A metal component swaging method comprising: providing a metal ball at an opening edge of a hole provided in a metal component, the hole having a central axis; pressing the metal ball in a direction of the central axis using a swaging tool such that a metal ball press-fitting portion of the swaging tool abuts on the metal ball to press-fit the metal ball into the hole, the metal ball press-fitting portion being positioned around the central axis; and pressing a swaging portion of the swaging tool onto the metal component in the hole to provide a stopper between the opening edge and a center of the metal ball in the direction of the central axis, the swaging portion being provided around the metal ball press-fitting portion, an outer diameter of the swaging portion decreasing toward the metal ball press-fitting portion.
 8. The metal component swaging method according to claim 7, wherein the metal ball press-fitting portion has a conical surface.
 9. The metal component swaging method according to claim 7, wherein the swaging portion has a conical surface.
 10. The metal component swaging method according to claim 7, wherein the swaging tool includes a press-fit depth control portion to abut on a surface of the metal component to control a press-fit depth of the metal ball into the hole.
 11. The metal component structure according to claim 6, wherein the stopper is provided along an entire circumference of the hole around the central axis.
 12. The metal component structure according to claim 6, wherein the inner diameter of the tapered part gradually decreases from the opening edge toward the stopper.
 13. The metal component swaging method according to claim 7, wherein the outer diameter of the swaging portion gradually decreases toward the metal ball press-fitting portion.
 14. The metal component swaging method according to claim 7, wherein the stopper is provided while the metal ball is press-fitted into the hole. 